You should feed a high quality staple cichlid diet such as Hikari Pellets.
Supplement with any frozen/freezedried bloodworm, molluscs, tubifex, krill, rivershrimp, daphnia etc
As for live foods, I guess most would be fine, some people collect earthworms, clean them and chop up!
I also feed mine some veg too, I have a severum and a sailfin so it's more for them but the others enjoy eating it too: courgette, round lettuce, squash, pumpkin, and peas. just make sure the veg have been washed and blanched, and peas need to be shelled, then squished.
As long as you're feeding a good varied diet, it's all good
if you want to enhance colours, e.g. the green on the GT also feed spirulina flakes/tablets occasionally. I'm pretty sure the Hikari pellets have caratenoid for red in anyway.